Caption: MODEL RELEASED. Teenage contraception. General practice doctor discussing oral contraception with a teenager. The oral contraceptive pill contains synthetic versions of one or both of the female sex hormones responsible for ovulation (production of an egg, or ovum). The pill acts to suppress ovulation and causes changes to the uterus (womb) to prevent fertilisation and pregnancy. This type of pill is taken daily for three weeks, with a break in the fourth week for menstruation.